Forums

Forums
Renewable Heating
Air Source Heat Pum...
Ecodan Pump Issues…...
 
Notifications
Clear all

Ecodan Pump Issues… Circulation pump turns off when heat pump compressor turns off

 
Page 3 / 3
Air Source Heat Pumps (ASHPs)
Last Post by ASHP-BOBBA 2 hours ago
26 Posts
5 Users
6 Reactions
133 Views
RSS
 JamesPa
(@jamespa)
Illustrious Member Moderator
Joined: 3 years ago
Posts: 3956
13/01/2026 10:18 pm  

Posted by: @ashp-bobba
↑

1) I have an ASHP with undersized emitters by 30%

2) I have an ASHP with oversize emitters by 30%

3) I have an ASHP with perfectly sized emitters at 104% 

Interesting and great that you are able to run experiments.  As a matter of interest what precisely do you mean by 'oversized'.  Surely any emitters can be right sized at the right flow temperature and if they are oversized at the flow temperature at which you are running them will overheat the room unless turned off from time to time or flow restricted.

Perhaps I have just answered my own question - do you mean oversized but flow restricted to bring the output back to the right value?

 


This post was modified 2 hours ago by JamesPa

4kW peak of solar PV since 2011; EV and a 1930s house which has been partially renovated to improve its efficiency. 7kW Vaillant heat pump.


   
ReplyQuote
 ASHP-BOBBA
(@ashp-bobba)
Prominent Member Member Professional Installer
Joined: 1 year ago
Posts: 345
13/01/2026 10:32 pm  

@jamespa sorry James, yes larger surface area, messing with the DT. also this allows even lower running temperature, technically you could over size the emitters to run at 20.5 flow rate to heat a room at 20 if there is enough surface area but this would mean UFH in every surface on all 6 sides of the cube room.

 

So what I am effectively doing is using a DT of 6 rather than 5 and running at ever lower flow rates. Dont get me wrong, most ASHP especially Vaillant and Ecodan use 5dt at the plate but they fault over to 6 often, so they effectively float, its why I call it a test, it may be that I am wrong and overall it just makes the same outcome on bigger rads with restricted flow. I have balanced all the rads on this circuit as close to 6 as I can.

I have asked Mitsi several times in the past if there is a way to tweak the DT on the programming but they told me there is not they said and if i find a way to do this at the moment I would breach their warranties, so I accept this on my test units. I am sure in the very near future there will be a standard DT 7 across the plate on most brands which will help with most installations in homes keeping the 22mm loop on retrofits.

I don't think this test will make the system for energy efficient as such, just a larger heat transfer so all of the generated heat is usable, minimising wastage, but we are talking 3% not larger gains.

 

I may be wrong though and we will see.

 

 

 

 


AAC Group Ltd covering the Kent Area for design, supply and installation of ASHP systems, service and maintenance, diagnostics and repairs.
Professional installer. Book a one-to-one consultation for pre- and post-installation advice, troubleshooting and system optimisation.


   
ReplyQuote
Page 3 / 3
Forum Jump:
  Previous Topic
Related Topics
Topic Tags:  Ecodan (34) , 11.2kw (1) , ashp (83) ,

Currently viewing this topic 1 user ( Sheriff Fatman ) and 1 guest.

Recently viewed by users: JohnnyB 60 minutes ago, trebor12345 50 minutes ago.



Share:

Join Us!

Worth Watching

Latest Posts

Click to access the login or register cheese
x Powerful Protection for WordPress, from Shield Security
This Site Is Protected By
ShieldPRO →